title of the thesis - Department of Geology - Queen's University

Table 3.1: Event characteristics in an intact and fractured rock mass
Events in intact rock mass (loading)
• High moment magnitude, M • Low M
• High seismic energy, E o • Low E o
• High seismic moment, M o • Low M o
• High apparent stresses, σ a • Low σ a
• Low source radius, R o • High R o
• Comparable dynamic and static stress drop
values (low complexity)
Events in yielded rock mass (post-peak)
• High dynamic stress drop as compared to static
stress drop (high complexity)
Spatial and temporal analysis of microseismic event parameters was conducted to identify trends
and assess rockmass properties on levels 7200, 7400 and 7530. Temporal analysis of levels and
clustered events on the 7400 Level did not reveal any significant trends (temporal parameter
results can be found in Appendix B) but did reveal comparable spatial event distributions: dense
seismicity extends from the southeastern corner of the excavation to an area southwest of the
excavation (Fig. 3.7). Events in this area occur sporadically during the two-year time period. It is
postulated that in the Creighton Deep the microseismic event distribution as well as the event
parameters reflect both local stress conditions and the physical state of the rock mass; heavily
damaged rock is expected to be aseismic, whereas a actively yielding rock mass will result in
denser seismic activity.
Seismicity on 7400 Level is separated into three distinct clusters (Table 3.2, Fig. 3.8). The first
cluster (Cluster 1) is located to the southwest of the excavation. Cluster 1 is the densest cluster and
has a markedly different seismic character from the other clusters. Cluster 1 contains elevated
source parameter values for seismic moment, energy, apparent stress, stress drop as well as
particle motion parameters that are well above background levels (Table 3.3).
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